With regard to a processing apparatus which processes a processing target object such as a semiconductor wafer with plasma of a processing gas or the like, there is known a gas supply apparatus configured to control a supply of the processing gas into the processing apparatus. Such a gas supply apparatus includes element devices such as a flow rate controller which control a flow rate of a gas, a plurality of valves which control a supply of the gas or a stop of the supply of the gas, and so forth. These element devices are connected with a pipeline through which the gas is flown, and are arranged on the same surface of a base.
Further, the element devices such as the flow rate controller or the valves are arranged on the same surface of the base, and neighboring element devices may be connected with a pipeline which penetrates the base. With this configuration, the element devices belonging to the gas supply apparatus can be densely arranged on the same surface of the base, so that the gas supply apparatus can be scaled down.
Patent Document 1: Japanese Patent No. 5,020,758
However, in a gas supply system which controls the supply of the processing gas into the processing apparatus, if the volume of the pipeline configured to connect the element devices of the gas supply system is large, it takes time to exhaust the processing gas remaining in the pipeline when replacing the processing gas flowing in the pipeline. Therefore, it is difficult to improve throughput in the processing apparatus which performs multiple processes while replacing the processing gases.
Furthermore, when replacing the processing gas at a high speed by opening or closing a valve, if the volume of the pipeline which connects the element devices of the gas supply system is large, the valve is opened before a pressure within the pipeline reaches a required level. In such a case, it is difficult to control the processing gas to have a required pressure.